c++ - 为什么 OpenCV 中的 DMatch 是结构体而不是类

Question

到目前为止我所见过的 C++ 接口(interface)中的所有其他类型都是一个类。为什么是DMatch here当文档说它是一个类时，仍然被列为结构:

“匹配关键点描述符的类:查询描述符索引、训练描述符索引、训练图像索引和描述符之间的距离。”

或者对类的引用是否不明确。只是寻找有关 OpenCV 为何仍在其 C++ 接口(interface)中使用结构的信息。

也在文件/opencv-master/modules/core/doc/basic_structs.rst

DMatch 似乎被记录为一个类，例如

    DMatch
    ------
    .. ocv:class:: DMatch

    Class for matching keypoint descriptors: query descriptor index,
    train descriptor index, train image index, and distance between descriptors. ::

        class DMatch
        {
        public:
            DMatch() : queryIdx(-1), trainIdx(-1), imgIdx(-1),
                       distance(std::numeric_limits<float>::max()) {}
            DMatch( int _queryIdx, int _trainIdx, float _distance ) :
                    queryIdx(_queryIdx), trainIdx(_trainIdx), imgIdx(-1),
                    distance(_distance) {}
            DMatch( int _queryIdx, int _trainIdx, int _imgIdx, float _distance ) :
                    queryIdx(_queryIdx), trainIdx(_trainIdx), imgIdx(_imgIdx),
                    distance(_distance) {}

            int queryIdx; // query descriptor index
            int trainIdx; // train descriptor index
            int imgIdx;   // train image index

            float distance;

            // less is better
            bool operator<( const DMatch &m ) const;
        };

Answer 1

没关系，我发现它也列在 CORE 文档中。 here作为如下的一个类...所以我就这样...不过还是感谢您的帮助

    Never mind, I found it was also listed in the CORE doc. [here](http://docs.opencv.org/trunk/modules/core/doc/basic_structures.html?highlight=dmatch#DMatch) as a class...so I'm just going with that...Thanks for the help on this though
    DMatch

    class DMatch

    Class for matching keypoint descriptors: query descriptor index, train descriptor index, train image index, and distance between descriptors.

    class DMatch
    {
    public:
        DMatch() : queryIdx(-1), trainIdx(-1), imgIdx(-1),
                   distance(std::numeric_limits<float>::max()) {}
        DMatch( int _queryIdx, int _trainIdx, float _distance ) :
                queryIdx(_queryIdx), trainIdx(_trainIdx), imgIdx(-1),
                distance(_distance) {}
        DMatch( int _queryIdx, int _trainIdx, int _imgIdx, float _distance ) :
                queryIdx(_queryIdx), trainIdx(_trainIdx), imgIdx(_imgIdx),
                distance(_distance) {}

        int queryIdx; // query descriptor index
        int trainIdx; // train descriptor index
        int imgIdx;   // train image index

        float distance;

        // less is better
        bool operator<( const DMatch &m ) const;
    };